A number of devices for collecting and testing bodily fluids (e.g., blood, urine and saliva) for the presence of analytes exist in the art. En the context of providing a relatively quick and inexpensive sample collecting device and associated testing system, there exists several approaches for collecting a sample fluid, expressing the sample fluid in a test device and performing an assay of the sample. Examples of these types of testing systems include U.S. Pat. Nos. 5,965,453; 6,027,943; 4,895,808; 4,943,522; 6,267,722 and 5,393,496.
Diagnostic systems for performing an assay of an expressed sample typically include a sample collector, a container for holding the sample collector and a testing apparatus. One type of sample collector typically includes an absorbent pad for absorbing the target fluid and a holder for holding the sample as the sample is being collected. The sample is then transferred to a sample container or test device by using one of a variety of known approaches including a mechanism for expressing the sample into a sample container, U.S. Pat. No. 5,268,148, dipping the sample collector into a test solution, U.S. Pat. No. 4,895,808, or using a second filter or absorbent pad to transfer the fluid from the collector pad to an intermediate container or test device. Sample collectors may also include a sponge or chemical reagent disposed on a filter strip which may indicate that an adequate sample is collected, U.S. Pat. No. 5,393,496.
One type of test device for detecting the presence of analytes in a fluid sample is a lateral flow test device, an example of which is described in U.S. Pat. No. 6,027,943. The device for performing a lateral flow test device typically includes the lateral flow test strip, a port or opening for delivery of the expressed sample to the test device and a viewing area for viewing the test strip (the test strip indicating whether the targeted analyte is present in the fluid sample). The test device may, or may not also include a buffer solution for mixing with the sample and a second viewing area for confirming that there was an adequate permeation of sample through the test strip, U.S. Pat. No. 6,187,598. The presence or absence of the target analyte may then be determined by, for example, visual inspection under ambient light or by exposing the test strip to different forms of electromagnetic radiation using an instrument.
Lateral flow tests, also known as strip tests and immunochromatographic assays are often used in applications for home testing, rapid point of care testing, and field testing for different environmental and agricultural analytes. This technology offers a range of benefits including being user-friendly, relatively inexpensive and offering quick results. A lateral flow test strip is composed of four main elements: the sample application pad, the conjugate release pad, the lateral flow membrane and the support pad. These components are then enclosed within a test device housing which may contain a window or other means to read the assay results.
Solid phase lateral flow devices incorporate a solid support strip which binds a member of a ligand-receptor pair. Porous materials such as nylon, nitrocellulose, cellulose acetate, glass fibers, and other porous polymers are often employed as solid support strips. The sample that may contain the targeted analyte flows along the solid support across the assay. Several procedures may be utilized including the analyte or its derivative, becoming bound to the reactant and the presence of the analyte or its derivative being detected, or the analyte or its derivative may react to form a product that is then detected. Examples of detectable labels are various chromogens, such as fluorescence, dyes, absorbents which may or may not require an instrument for detecting the label.